An Garda Síochana has said that Commissioner Noirín O'Sullivan 'occasionally' used a Gmail account due to size & storage limits with the internal email system.

A Sunday Times report yesterday highlighted the Commissioner's use of a private email account.

In a statement this evening, the force says: "Due to restrictions with the Garda email system such as e-mail size and storage, the Commissioner occasionally used a Gmail address to ensure that Garda business has been discharged effectively. At all times, there has been due regard to the sensitivity of any information being transmitted in this way.

"Such issues with the Garda email system were identified by the Garda Inspectorate 2015 Report and are currently being addressed as part of the organisation’s mobility strategy."

According to the statement, Commissioner O'Sullivan "takes all recommended security measures" when using Gmail, including regularly changing the password.

"An Garda Síochána is satisfied that the Commissioner's systems are secure and there is no evidence that they have ever been compromised," the statement explains. "The Commissioner is well aware of her obligations to protect national security and policing operations and would under no circumstances allow them to be compromised."

The statement adds that the Commissioner will submit a report on the issue to the Department of Justice and the Policing Authority.